@@ -55,7 +55,7 @@ static int button_adc_of_to_plat(struct udevice *dev)
struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev);
struct button_adc_priv *priv = dev_get_priv(dev);
struct ofnode_phandle_args args;
- u32 threshold, up_threshold, t;
+ u32 down_threshold = 0, up_threshold, voltage, t;
ofnode node;
int ret;
@@ -78,7 +78,7 @@ static int button_adc_of_to_plat(struct udevice *dev)
return ret;
ret = ofnode_read_u32(dev_ofnode(dev), "press-threshold-microvolt",
- &threshold);
+ &voltage);
if (ret)
return ret;
@@ -87,13 +87,24 @@ static int button_adc_of_to_plat(struct udevice *dev)
if (ret)
return ret;
- if (t > threshold)
+ if (t > voltage && t < up_threshold)
up_threshold = t;
+ else if (t < voltage && t > down_threshold)
+ down_threshold = t;
}
priv->channel = args.args[0];
- priv->min = threshold;
- priv->max = up_threshold;
+
+ /*
+ * Define the voltage range such that the button is only pressed
+ * when the voltage is closest to its own press-threshold-microvolt
+ */
+ if (down_threshold == 0)
+ priv->min = 0;
+ else
+ priv->min = down_threshold + (voltage - down_threshold) / 2;
+
+ priv->max = voltage + (up_threshold - voltage) / 2;
return ret;
}
In the Linux implementation of adc-keys (drivers/input/keyboard/adc-keys.c), `press-threshold-microvolt` is not really interpreted as a threshold, but rather as the "nominal voltage" of the button. When the voltage read from the ADC is closest to a button's `press-threshold-microvolt`, the button is considered pressed. This patch reconciles the behavior of button-adc with Linux's adc-keys such that device trees can be synchronized with minimal modifications. Signed-off-by: Peter Cai <peter@typeblog.net> --- drivers/button/button-adc.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)